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I once had a very affordable 25mm Ortho which worked very well on DSOs. Don't know what one would cost these days.

just so happens i own a lovely 25mm ortho

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the answer is the one that fits the object nicely in the field. your 25mm ortho may fit the bill, especially with your new toy. at darker sites I have used my 32mm TV Plossl and it was lovely giving about 2 degrees.

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I've just been looking on the explorescientific.de site at the Maxvision 68deg EPs. If they are the short term Meade 5000 SWAs for a knockdown price that they look like, then they are one heck of a lot of EP for the money. As a Meade, they were what? £150 each? The 24mm is 88.8 Euro shipped, meaning approximately £75 at your door, the 16mm £59.

I had and rated the BSTs for the money, but at that price for a quality SWA in a 1.25" format, I'm not sure I'd go for three BSTs over two of the Maxvisions. For instance I have 30, 18 & 14mm UWAs and I tend to jump straight past the 18mm. With a 24 & 16mm squeezing that gap further, I'd argue the 18mm (even if you do go BST) is a bit redundant.

Hang around and I'll tell you what the 24mm is like when mine turns up. :)

Russell

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Jules, from my experience most of the DSOs I view (globs, galaxies, nebulae) is being done at 90x and at 125x. Obviously, one can go higher on some of them but this range generally hits the mark. It is a kind of sweet spot in my own f/5.

Following Shane's sound advice when I asked him a similar question, I'd buy a Tele Vue Plossl second hand at the focal length required and see if it fits the bill. If it does you have a keeper, if it doesn't you sell it on for just about the same price you bought it for. A win win situation.

After that - and you don't really need many TVPs - you may want to save for a premium-premium eyepiece in that given focal length, or which offers that give AFOV, that is, an EP that can offer a similar performance to the TV plossl but perhaps with a more forgiving eye-relief or one offering a wider field, or a little or both.

I really don't think this stage requires any hurry and feel it is better to save for one premium-premium EP in 6 months, say, than filling in with 'stop-gaps' that in the end still leave us wanting more and losing out when we re-sale.

Not sure if I said anything you didn't know already.

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I suspect that the BST Starguiders will be one of the best options, reasonable field of view and work pretty good in f/5 scopes from the various reports. They have a fair few options depending on the magnification and field of view you require.

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Jules, if I'm mistaken I hope you or someone with more experience in this will correct me here, but I've been having a think and reckon that if you have a 6" f/5, perhaps the better magnification would be around 60x to 90x for DSOs (rather than 90x to 125x I stated above which had the 10" in mind). The reason I say this is simply from a gut feeling, nothing practiced, and from playing around with the 4" and 10".

Unless I'm beating up the wrong bush, I think you're got a lovely 6" f/5 which would have a focal length of around 750mm. If this is so, the TVP advice is perhaps not the best. I mean, to get around that 90x, say, we're going to have to get an 8mm plossl which isn't going to be that great on the eye-relief front.

Personally, I would prefer to use a 9mm Ortho for its cracking sharpness and contrast, rather than a widerfield, kinder eye-relief but lesser performance quality EP. In the end I sold up all my X-Cel LXs, not because they were bad EPs - I prefered them to the Hyperions I used and imagine they would be a tack better than BSTs - but because they just didn't have that Ortho quality to the image in the f/5.

And with you being a seasoned planet, lunar and frac man, I fear that a sloppy EP in your own f/5 is just going to let you down.

So, if permitted, I'd like to make a little ammendment to what I said above. If it were me, knowing what I know now, and not having it completely clear what is in your EP case, I'd be hunting for a 9mm BGO on the secondhand market and for the 60x range a Tele Vue 11mm plossl. Two cracking EPs - two lifers - that won't set you back much more than a 100 notes.

Now, there are folk that say tracking a planet, or DSO with such narrow AFOV in a dob or on an AZ4 is troublesome, but I've never had a problem. It sounds silly, but the planet doesn't suddenly move any faster than it did in the frac and I feel so long as you don't have a problem with the Tal, there isn't going to be one with the newt.

After that, as suggested, I'd put away 50 a month and in six months time, in the season of darkness, get a really saucy EP. To be honest, I'm growing towards the opinion that we don't need more than 3 EPs for general viewing: a long focal length for hunting, and the two mid-rangers (for 6" - 60x & 90x; for 10" - 90x & 125x). Planet and detail lunar work is another story, but you know that already.

I'm sorry if I've caused any more confussion.

Edited by Qualia
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The modified, inexpensive (26gbp) erfle with 66deg field have 13mm (and up) eye relieve, for both the 6 and 9mm version, so those are defenately worth a look.

Even though the lens design has limits when it comes to scopes around f/5, the area that's still sharp from the 66deg afov should be sufficient, and personally I am not bothered by a little outer field showing bigger stars. I don't have them in that focal length, but I suppose they reach that with a internal barlow element, so it might not be critical @ f/5 at all.

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Have a go with your Orthos and BST's before forking over any more cash Jules. I suspect your Orthos will be great but your BST's may leave you a little underwhelmed. If you were considering a wider aFOV (rather than just lower magnification) the unbranded Meades talked about above would be good or ES if you can stomach the hassle of importing the things!

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+1 to Rik's advice. We all over complicate things by thinking our gear isn't up to the job. But, unless you're getting annoyed at or noticing the eyepiece faults in the eyepieces that you already have, stick with what you've got.

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Yes, I would stick with what you have for now and see how you get on with the new set up. Those BST's will do you fine for now, I was pleasantly surprised at how good they performed so there is no hurry. If you get hooked then a 10mm Delos would be a damned useful eyepiece for use in all of your scopes..;) So it may well be worth going a little silly at some point huh!

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I will go with Stargazer00 answer of the Meade SWA lookalike the Maxvision, they come in 16, 20, 24, 28, 34, and 40mm. If they are indeed a Meade cancelled order they are going to be difficult to better without going to Pentax XW's or Panoptic's. Alan.

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I will go with Stargazer00 answer of the Meade SWA lookalike the Maxvision, they come in 16, 20, 24, 28, 34, and 40mm. If they are indeed a Meade cancelled order they are going to be difficult to better without going to Pentax XW's or Panoptic's. Alan.

That is what I said a few posts earlier in post #10.

Russell

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I actually think Qualia has a good point on the magnificaiton best used in a 6" F5 for DSO. I have one of these as my G&G (it's A+)

I typically use an ES 8.8mm for DSO in this scope and that gives 85x magnification and 1.75mm exit pupil. Bang on really for DSO, especially with the expansive 82 degree AFOV. TFOV in this scope with this eyepiece is just a hair over 1 degree which again makes for very pleasing DSO viewing.

In my longer focal length 10" I use a 14mm for the same job, same eyepiece range. 14mm in the 10" gives 85x, 3mm exit pupil, and the same 1.03 degree TFOV over an 82 degree AFOV.

The fact that I use 85x in both my scopes for galaxy and open cluster observing cant be a coincidence. there was nothing mathematical about this I just plonk all the eyepieces in until I find the one that works for the subject and these 2 on the suggested 'scopes are a sweetspot for me for these objects.

Globs on the other hand need more magnification. The 6" usually bears a 6.7mm (111x, 1.35mm pupil) eyepiece for these and the 10" wears the 8.8mm (136x, 1.86mm exit pupil). Although I can push them to one more eyepiece in the range if the subject warrants it.

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I tend to go a little higher on globular clusters especially in the 12 inch, I find the 20mm Nagler giving X152 is right on the money, it's going to be interesting to see what the 21mm E makes of the situation. I find other deep space objects like galaxies just a little disappointing, though it is nice to glimpse something that from time to time, maybe I need a bigger telescope, now there's an idea. Alan.

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I tend to go a little higher on globular clusters especially in the 12 inch, I find the 20mm Nagler giving X152 is right on the money, it's going to be interesting to see what the 21mm E makes of the situation. I find other deep space objects like galaxies just a little disappointing, though it is nice to glimpse something that from time to time, maybe I need a bigger telescope, now there's an idea. Alan.

You might need to sell some eyepieces for that Alan - not really an option (as you don't really want to be hearing "Why are you getting that again? You only sold it x weeks/months ago").

Interestingly enough, I prefer low magnification views of most DSOs and almost exclusively use my 26mm for them (25x), it might be that I don't really have any mid-range eyepieces, but it's usually a case of if I can see it, I don't want to increase the magnification in case I can't see it. Mind you, it is rather annoying when something appears as a smudge the size of a pea, and you're never sure whether you've seen it or not.

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I'm often using 200x plus on globular clusters and the brighter planetary nebulae with my 12" dob. M13 fills a good chunk of the field of view of the 6mm Ethos at 265x. It's also nice to drop back as well though and see the object in the context of it's star field. The little smoke ring of M57 sitting incongruously amidst the Lyra stars in a wide field is rather lovely :smiley:

I don't really feel there is such a thing as a DSO eyepiece as DSO's come in so many shapes and sizes :smiley:

Selling something and then finding you need to re-buy it again is an experience that I've been through a few times though :rolleyes2:

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